Rotating heat exchanger and method for sealing the same

ABSTRACT

The invention relates to a rotating heat exchanger ( 1 ) with a rotatably mounted rotor ( 3 ), comprising a first flow sector ( 4 ), for external ( 5 ) and supply air ( 6 ) and a second flow sector ( 7 ), for exhaust ( 8 ) and venting air ( 9 ), through which the above runs on rotating and a housing ( 2 ), enclosing the rotor ( 3 ) around the circumference thereof, whereby to improve the sealing of the rotor ( 3 ), the housing ( 2 ) around the circumference thereof is filled with housing or sealing air, whereby the pressure of the housing or sealing air is higher than the pressure of the airflows ( 5, 6; 8, 9 ) flowing through the rotor ( 3 ).

The invention relates to a rotating heat exchanger with a rotatably mounted rotor, which has a first flow sector for external and supply air and a second flow sector for exhaust and venting air, through which it runs upon rotating, and a housing which encloses the rotor at its periphery, and to a method for the sealing of such a rotating heat exchanger.

With known rotating heat exchangers of this kind, peripheral seals are provided between the rotor and the housing enclosing it at the front end face of the rotor and at the rear end face of the rotor, by means of which peripheral seals the exit of air from the airflows flowing through the rotor into the housing is to be prevented. Since the rotor rotates with respect to the housing enclosing it, considerable leaks between the rotor on the one hand and the housing on the other hand always occur during the operation of a rotating heat exchanger of this kind, which can lead to air from the airflows flowing through the rotor exiting from the rotor. This can lead to the supply air for a room made available by the rotating heat exchanger becoming undesirably contaminated.

The problem underlying the invention is to develop a rotating heat exchanger and a method for sealing one such rotating heat exchanger in such a way that such leaks in an undesired direction can no longer take place.

This problem is solved according to the invention by the fact that the housing enclosing the rotor at its periphery is filled with housing or sealing air, and that the pressure of the housing or sealing air is higher than the pressure of the airflows flowing through the rotor. As a result of the pressurisation of the housing with housing or sealing air under excess pressure, the pressure level in the housing is always kept above the pressure level of the airflows flowing through the rotor of the rotating heat exchanger. It is thus possible to prevent external and supply air being mixed with exhaust and venting air through the housing.

Furthermore, in the case of the rotating heat exchanger according to the invention, peripheral seals can obviously also be provided, by means of which the housing or sealing airflow can be reduced. Such peripheral seals can be fixed in an advantageous way on the housing of the rotating heat exchanger.

The pressure of the housing or sealing air can be kept at a constant pressure level. It must be taken into account here that this constant pressure level lies above the pressure level of the airflows flowing through the rotor of the rotating heat exchanger.

Alternatively, it is possible to keep the pressure of the housing or sealing air above the pressure of the airflows flowing through the rotor by a constant differential pressure. With this mode of procedure, the amount of housing or sealing air by means of which the housing must be pressurised can be optimised, whereby a sufficient excess pressure is always present inside the housing.

The excess pressure inside the housing can be produced to advantage by means of an external or internal pressure source.

According to an advantageous embodiment, the rotating heat exchanger according to the invention includes a control and regulating device, by means of which the operation of the pressure source can be controlled and regulated according to the signal of a pressure sensor measuring the pressure in the housing and/or a pressure sensor measuring the airflows flowing through the rotor. Accordingly, the pressure level of the housing or sealing air in the housing is controlled or regulated in dependence on the pressure level in the housing, which is based on a setpoint pressure, and/or the pressure level of the airflows flowing through the rotor.

Especially in places of use and cases of application in which there are present in the exhaust or venting air charges and compositions which can give rise to a risk of explosion for example, it is advantageous for the housing to be pressurised with non-critical housing or sealing air, because then the critical contents of the exhaust or venting air can be diluted, so that the explosion protection can be dispensed with, for example, in the combustion areas for driving motors.

According to an advantageous embodiment of the rotating heat exchanger according to the invention, airflow separation devices are provided running diametrically at the end faces of the rotor between the two flow sectors, said airflow separation devices being connected to the housing and able to be supplied with a sealing airflow by means of the housing or sealing air present in the housing. A fan, which is otherwise required for the airflow separation devices, can be dispensed with in the case of the rotating heat exchanger according to the invention. If a rinsing wedge-like device, which is connected to the housing and able to be supplied with a rinsing airflow by means of the housing or sealing air present in the housing, is provided at the end face of the rotor in the region of the flow sector for the exhaust and venting air that is arranged—in the rotary direction of the rotor - directly before the flow sector for external and supply air, it is also possible to dispense with a separate fan for supplying the rinsing wedge-like device. If the rotating heat exchanger according to the invention is provided according to an advantageous development with a temperature-regulating device, by means of which the housing or sealing air can, e.g. for the purpose of anti-icing, be temperature-regulated, any icing on the peripheral seals can be prevented, whereby the formation of condensate in the housing can also be eliminated. The housing or sealing air can be taken in a straightforward manner from the supply and/or external air system of the rotating heat exchanger.

To advantage, nozzle devices are provided on the housing of the rotating heat exchanger according to the invention, through which nozzle devices housing or sealing air can be directed onto a bearing of the rotor. As a result, the bearing of the rotor can be kept dry with relatively little outlay.

The invention will be explained below in greater detail with the aid of an embodiment, reference being made to the drawing.

In the figures:

FIG. 1 shows a view of a rotating heat exchanger designed according to the invention; and

FIG. 2 shows a schematic representation of airflows flowing through a rotor of the heat exchanger according to the invention and of sealing and rinsing airflows with a rotating heat exchanger designed according to the invention.

A rotating heat exchanger 1 according to the invention shown in perspective view in FIG. 1 has a housing 2 approximately square in terms of its external contour in the embodiment shown.

Housing 2 encloses a rotor 3 of rotating heat exchanger 1 at the periphery of the former.

Rotor 3 has a first flow sector 4, through which external air 5 and supply air 6 flows, as can be seen from FIG. 2. The airflow for external air 5 and supply air 6 is represented by arrows in FIG. 2.

Furthermore, rotor 3 has a second flow sector 7, through which exhaust air 8 and venting air 9 flows in the opposite direction to external air 5 and supply air 6. The airflow formed by exhaust air 8 and venting air 9 is also shown by arrows in FIG. 2.

Rotor 3 of the rotating heat exchanger is arranged so as to be rotatable about a bearing or a hub 10. The direction of rotation of rotor 3 is shown by arrow 11 in FIG. 1 and FIG. 2.

Housing 2 is connected to a pressure source not shown in FIGS. 1 and 2, by means of which housing 2 is pressurised with housing or sealing air, and more precisely at a pressure which is higher than the pressure level in airflows 5, 6; 8, 9 flowing through rotor 3. As a result, an exit of exhaust air 8 or venting air 9 from rotor 3 in the radially outward direction is prevented. Correspondingly, an exit of external air 5 and supply air 6 from rotor 3 in the radially inward direction is also prevented. Sealing airflow 12 represented by arrows 12 and running radially inwards with respect to rotor 3 enters into the airflow formed by external air 5 and supply air 6 and the airflow formed by exhaust air 8 and venting air 9. A controlled chamber air seal for rotating heat exchanger 1 is created, as it were, by housing 2 which is under excess pressure.

Peripheral seals 15, 16 are provided respectively between the periphery of rotor 3 and front side 13 of housing 2 enclosing rotor 3 and correspondingly provided rear side 14 of housing 2, by means of which peripheral seals the leaks between housing 2 on the one hand and rotor 3 on the other hand, which necessarily occur during the operation of rotating heat exchanger 1, are to be the kept as small as possible.

These peripheral seals 15, 16 are expediently fixed at front side 13 and at rear side 14 of housing 2, so that the external periphery of rotor 3 moves with respect to these peripheral seals 15, 16.

The pressure of the housing or sealing air inside housing 2 is either kept at a constant pressure level, whereby this pressure level is selected in such a way that, at all events, it lies above the pressure level of airflows 5, 6; 8, 9 flowing through rotor 3. Alternatively, it is possible to control and regulate the pressure of the housing or sealing air inside housing 2 in such a way that this pressure always lies above the pressure level in airflows 5, 6; 8, 9 flowing through rotor 3 by a predeterminable differential pressure.

An external or an internal pressure source can be provided as a pressure source.

By means of a control and regulating device not shown in the figures, which includes a pressure sensor arranged in housing 2 and a pressure sensor detecting the pressure in external air 5 and supply air 6 and in exhaust air 8 and venting air 9. The pressure inside housing 2 is controlled or regulated according to the signals of these pressure sensors. A setpoint pressure inside housing 2 or a differential pressure between the pressure in housing 2 and the pressure inside airflows 5, 6; 8, 9 can be used as a target magnitude.

If at least one airflow that is critical from the composition standpoint flows through rotor 3 of rotating heat exchanger 1, it is expedient for housing 2 to be pressurised with non-critical housing or sealing air. Said critical airflow can be diluted by means of this non-critical housing or sealing air, in such a way that the risks resulting from the composition of the critical airflow, e.g. risk of explosion, are reduced.

An airflow separation device 19 and 20 extending horizontally and diametrically over rotor 3 is provided respectively at two end faces 17, 18 of rotor 3. The two airflow separation devices 19, 20 are designed, as it were, as central crosspieces, the interior space whereof communicates with the interior space of housing 2, so that the two airflow separation devices 19, 20 are pressurised with housing or sealing air under excess pressure. There emerges from the two airflow separation devices 19, 20 a sealing airflow shown by arrows 21, by means of which mixing of external air 5 and venting air 9 is prevented at end face 17 of the rotor and mixing of supply air 6 and exhaust air 8 is prevented at end face 18 of rotor 3.

Furthermore, a rinsing wedge-like device 22 is arranged at end face 17 of rotor 3 beneath airflow separation device 19. The rinsing wedge-like device directs a rinsing airflow shown by arrows 23 through rotating rotor 3, so that co-rotating air from second flow sector 7, which is assigned to exhaust air 8 and venting air 9, is prevented from passing into first flow sector 4 of rotor 3, which is assigned to external air 5 and supply air 6. With the rotating heat exchanger shown in FIGS. 1 and 2, rinsing wedge-like device 22 is connected—like the two airflow separation devices 19, 20—to housing 2, so that rinsing airflow 23 is also fed through housing or sealing air from housing 2.

Furthermore, rotating heat exchanger 1 shown in FIGS. 1 and 2 is equipped with a heating device not shown in the figures, by means of which the housing or sealing air can be heated. In the case of certain requirements, however, it may also be expedient generally to provide a temperature-regulating device, by means of which the temperature of the housing or sealing air inside housing 2 can be temperature-regulated at will. The aforementioned heating device is especially expedient when icing of rotating heat exchanger 1 is to be prevented in the presence of certain temperature conditions.

The housing or sealing air can be taken from the supply air system or the external air system of rotating heat exchanger 1.

Housing 2 can be provided with nozzle devices, not shown in FIGS. 1 and 2, through which bearing or hub 10 of rotor 3 of rotating heat exchanger 1 can be kept dry. This is of special importance particularly in the case of rotating heat exchangers 1 in which airflows 5, 6; 8, 9 flowing through rotor 3 are subjected to humidity. 

1. A rotating heat exchanger (1), with a rotatably mounted rotor (3), which has a first flow sector (4) for external air (5) and supply air (6) and a second flow sector (7) for exhaust air (8) and venting air (9), through which it runs upon rotating, and a housing (2) which encloses the rotor (3) at its periphery, characterized in that the housing (2) encasing the rotor (3) at its periphery is filled with housing or sealing air, and that the pressure of the housing or sealing air is higher than the pressure of the airflows (5, 6; 8, 9) flowing through the rotor (3).
 2. The rotating heat exchanger according to claim 1, wherein peripheral seals (15, 16) are arranged between the periphery of the rotor (3) on the one hand and the housing (2) on the other hand.
 3. The rotating heat exchanger according to claim 2, wherein peripheral seals (15, 16) are fixed to the housing (2).
 4. The rotating heat exchanger according to claim 1, wherein the pressure of the housing or sealing air can be kept at a constant pressure level.
 5. The rotating heat exchanger according to claim 1, wherein the pressure of the housing or sealing air can be kept at a constant differential pressure above the pressure of the airflows (5, 6; 8, 9) flowing through the rotor (3).
 6. The rotating heat exchanger according to claim 1, with an external or internal pressure source, by means of which the excess pressure in the housing (2) can be produced.
 7. The rotating heat exchanger according to claim 1, with a control and regulating device, by means of which the operation of the pressure source can be controlled or regulated according to the signal of a pressure sensor measuring the pressure in the housing (2) and/or a pressure sensor measuring the pressure of the airflows (5, 6; 8, 9) flowing through the rotor (3).
 8. The rotating heat exchanger according to claim 1, the housing (2) whereof can be pressurized with non-critical housing or sealing air.
 9. The rotating heat exchanger according to claim 1, with airflow separation devices (19, 20) arranged running diametrically at the end faces (17, 18) of the rotor (3) between the two flow sectors (4, 7), said airflow separation devices being connected to the housing (2) and being able to be supplied with a sealing airflow (21) by means of the housing or sealing air present in the housing (2).
 10. The rotating heat exchanger according to claim 1, wherein a rinsing wedge-like device (22), which is connected to the housing (2) and able to be supplied with a rinsing airflow (23) by means of the housing or sealing air present in the housing (2), is provided at the end face (17) of the rotor (3) in the region of the flow sector (7) for the exhaust air (8) and venting air (9) that is arranged—in the rotary direction (11) of the rotor (3)—directly before the flow sector (4) for external air (5) and supply air (6).
 11. The rotating heat exchanger according to claim 1, with a temperature-regulating device, by means of which the housing or sealing air can, e.g. for the purpose of anti-icing, be temperature-regulated.
 12. The rotating heat exchanger according to claim 1, wherein the housing or sealing air can be taken from the supply air and/or the external air system of the rotating heat exchanger (1).
 13. The rotating heat exchanger according to claim 1, wherein nozzle devices are provided on the housing (2), through which nozzle devices housing or sealing air can be directed onto a bearing (10) of the rotor (3).
 14. A method for sealing a rotating heat exchanger (1), characterized in that a housing (2) enclosing a rotor (3) of the rotating heat exchanger (1) at the periphery of the rotor (3) is pressurized with housing or sealing air and the pressure of the housing or sealing air in the housing (2) is kept above the pressure level of airflows (5, 6; 8, 9) flowing through the rotor (3) of the rotating heat exchanger (1).
 15. The method according to claim 14, wherein the pressure level of the housing or sealing air in the housing (2) is kept constant.
 16. The method according to claim 14, wherein the pressure level of the housing or sealing air in the housing (2) is kept above the pressure level of the airflows (5, 6; 8, 9) flowing through the rotor (3) by a constant differential pressure.
 17. The method according to claim 14, wherein the pressure level of the housing or sealing air in the housing (2) is controlled or regulated in dependence on the pressure level in the housing (2) and/or the pressure level of the airflows (5, 6; 8, 9) flowing through the rotor (3).
 18. The method according to claim 14, wherein the housing (2) is pressurized with noncritical housing or sealing air.
 19. The method according to claim 14, wherein airflow separation devices (19, 20) arranged at the end faces (17, 18) of the rotor (3) are supplied from the housing (2) with housing or sealing air.
 20. The method according to claim 14, wherein a rinsing wedge-like device (22) of the rotor (3) is supplied from the housing (2) with housing or sealing air as rinsing air.
 21. The method according to claim 14, wherein the housing or sealing air is temperature-regulated.
 22. The method according to claim 14, wherein the housing or sealing air is taken from the supply air and/or external air system of the rotating heat exchanger (1).
 23. The method according to claim 14, wherein bearings (10) of the rotor (3) are acted upon by housing or sealing air. 